Relative toxicity of some newer insecticide molecules against vector and sucking pest complex of okra

Abstract

Sucking pest like leaf hoppers or jassid (Amrasca biguttula biguttula (Ishida)) and vectors i.e., whitefly (Bemisia tabaci (Gennadius)) are regarded as one of the major biotic stresses in okra cultivation in India. Apart from direct sucking the plant sap and thereby devitalizing the crop through their specially adapted mouthparts, many of them also act as vectors for important plant diseases like okra yellow vein mosaic and okra enation leaf curl disease. To control these sucking pests and vectors, several newer insecticide molecules were tested under open field conditions during Kharif seasons of 2021 and 2022. Based up on the two years of pooled data, among the tested insecticides, Tolfenpyrad 15% EC @ 2 ml/L was the best molecule in reducing leaf hopper population in okra (5.40 per leaf) with 63.49% reduction over control (PROC). The next best molecule was flupyradifurone 17.09% SL (5.70 jassids per leaf with 61.46 PROC). In the case of whitefly, flupyradifurone 17.09% SL was the most promising during both years with percent population reductions of 69.90 over control. The next best molecule in the list was tolfenpyrad 15% EC with 67.08 PROC. Interestingly, Imidacloprid-treated plots had the highest leaf hopper (10.39 per leaf) and whitefly (9.55 per leaf) population among all treatments indicating its low activity against these sucking pests of okra. The highest healthy green fruit yields (152 q/ha) were obtained from the plots treated with tolfenpyrad 15% EC with a maximum cost-benefit ratio of 1:2.19 followed by dinotefuran 20% SG (1:2.16) and acetamiprid 20% SP (1:2.15).